This invention concerns the monitoring of a diesel engine operation, and more particularly a monitor for monitoring the engine exhaust gas temperature for each cylinder in the engine.
To monitor the operation of a diesel or gas engine it is desirable to monitor the exhaust gas temperature of each cylinder. The exhaust gas temperature on a diesel engine will indicate the overloading or underloading of an individual cylinder by causing a high temperature or a low temperature respectively; however, an abnormal operating temperature may also indicate such other faults as inadequate ebgine cooling, excessive friction in the cylinder, partial piston seizures or an inadequate air supply to the cylinder.
It would be useful to compare the exhaust gas temperature of each cylinder with the average of all the other cylinders on the engine so that normal changes in the exhaust gas temperature (EGT) due to a change in load or other factors affecting all the cylinders will not alarm the monitor but a problem with an individual cylinder will cause an alarm.
Furthermore, an accurate monitoring system of the entire engine operation allows the engine to be operated more efficiently and balancing each cylinder to the overall average may result in a fuel savings as well as a more efficient operation of the engine.
Previous analog systems could mechanically scan a set of cylinders; however, they were not as accurate as a digital system. There was no computed average as the analog signals from the other cylinders were placed in parallel and were balanced against the cylinder being tested. Furthermore these previous systems could not account for an open thermocouple which causes an erroneous reading from the system.